This invention relates to the field of steam separators, and is directed more particularly to a cyclone steam separator that is utilized to process fluids received from a geothermal well, and which has an improved baffle plate arrangement between the steam and water chambers of the separator vessel.
The present so-called energy crisis has caused alternative sources of energy heretofore not considered attractive to become more attractive. One of these sources is geothermal energy. One introductory publication relating to geothermal energy is "The Basic of Applied Geothermal Engineering" by E. F. Wehlage and published in 1976 by Geothermal Information Services, 318 Cherrywood Street, West Covina, Calif. 91794.
Geothermal well fluid consists primarily of steam and water, and it is this steam which can be utilized by steam-operated power generators. However, in order to obtain optimum generation of power, only steam of the highest quality should be passed on to the power generator. The important burden of producing high quality steam from geothermal well fluid rests on the steam separator. Therefore, it can be seen that a steam separator in a geothermal well production setup performs a very important function.
In cyclone-type steam separators, the water droplets of an incoming steam-water mixture impinge against the inside surface of the separator vessel due to the centrifugal forces developed by the swirling motion of the fluid as it enters the vessel. The water then flows into a water collection chamber from which it passes to be disposed of in some acceptable fashion. The steam is relatively uneffected by this centrifugal action and rises into a steam chamber located near the top of the vessel. The steam exits the steam chamber through a steam outlet and is then transported for use in generating power or for other purposes. In a bottom outlet type of steam separator, a vertical steam outlet conduit extending between the water and steam chambers receives steam from the steam chamber and directs it out at the bottom of the vessel. In a top outlet type of steam separator, the steam rises and exits directly through the top of the vessel.
Heretofore, steam separators have utilized a baffle plate to separate and isolate the steam chamber from the water chamber. A central opening in the baffle plate allows the steam outlet conduit (in a bottom outlet type of separator) to pass between the steam and water chambers, and accommodates the passage of water downwardly through the baffle and into the water chamber. In one such steam separator, the outside edge of the baffle plate is connected to the vessel wall so that the centrifugal movement of the fluid causes the water to collect, for the most part, on or near the vessel wall a considerable distance radially outwardly of the annular opening. Consequently, the water does not always pass into the water collection chamber fast enough and in sufficient quantities to properly isolate the water and steam in the separator vessel. Swirling fluid above the baffle plate tends to sweep up any water standing on the baffle so that effective separation of the steam from the water is not achieved with this structure.
One attempt that has been undertaken to overcome this problem has been to employ a special outer loop element for the purpose of directing water from above the baffle plate to the water chamber located below it. The loop element is in the form of a C-shaped conduit which connects at one end with the vessel wall in the area immediately above the baffle and at the opposite end of the vessel wall at a location below the baffle. Although loop devices of this nature function in a generally acceptable manner with respect to directing wall past the baffle plate and allowing steam to exit the water chamber through the annular space defined between the steam outlet conduit and central opening, they have not been entirely satisfactory in other respects. Most notably, the need for the loop element adds to the cost and complexity of the steam separator and to the assembly difficulties. Moreover, the loop receives water at only a single location in the circumference of the vessel, and water at remote locations is delayed entering the loop for passage into the water collection chamber. The loop also complicates the structure and maintenance difficulties in that it is mounted to the outside wall of the vessel at an exposed location. Another problem is that corrosion and other damage to the loop can detract from its ability to function properly and can thus have a significant adverse effect on the performance of the steam separator.
In another embodiment, which has a central opening to receive the steam outlet conduit, the baffle plate is supported by a plurality of flanges that depend from the bottom surface of the baffle and are connected to the vessel wall so that the outside edge of the baffle plate is spaced apart from the vessel wall. These flanges are generally perpendicular to the direction of flow of fluid entering the water chamber and effectively prevent the formation of a vortex in the water chamber. However, the sudden collision of the swirling fluid with these perpendicular elements creates turbulence within the water chamber. Fine water droplets created by the turbulence are caught up in the steam updraft and carried along with the steam through the annular space defined between the steam outlet conduit and central opening thereby lowering the quality of the steam delivered from the separator. It is desirable that fluid be able to enter the water chamber in a manner so that a vortex is not created and with a minimum amount of turbulence.
The present invention is an improvement over the invention shown and described in copending U.S. patent application Ser. No. 031,722 filed Apr. 20, 1979 by William L. Godare, now U.S. Pat. No. 4,263,025. The cyclone steam separator shown in application Ser. No. 031,722 has a horizontal baffle plate with a series of openings spaced around its periphery and an upwardly projecting scoop adjacent each opening to direct the swirling fluid (mostly water with some steam) therethrough. The scoops are located next to the inner surface or wall of the separator vessel and are open on the end facing the swirling fluid in the vessel as well as on the inside. The fluid on the baffle tends to enter the scoops due to the centrifugal action of the swirling fluid and the fluid thus is directed downwardly through the openings into the water chamber located below the horizontal baffle plate.
Although this steam separator operates satisfactorily, under certain conditions of use, steam sometimes collects in the water chamber below the horizontal baffle, and it is desirable to remove from the water chamber the steam which is discharged by the swirling fluid below the baffle plate. Fluid oftentimes impinges the external surface of the horizontal portion of the scoops and does not pass into the water chamber. It is desirable that this fluid travel directly into the scoop openings. Fluid also oftentimes impinges the internal surface of the vertical portion of the scoop and splashes out of the scoop. Although others utilized a rim around the central opening in the baffle plate to assist separation of upwardly moving steam and downwardly swirling fluid stream, it is desirable that this well fluid be retained within the scoop.